Monitoring horses requiring surgery for colic

Anaesthetic for colic surgery

Horses that colic and require surgery should be monitored closely for changes in cardiovascular, respiratory and metabolic status and exacerbation of pain. Sedation should be individualised and anaesthesia produced by administering a combination diazepam (or midalzolam) and ketamine and maintained with isoflurane or sevoflurane amd appropriate adjunctive analgesic infusions (lidocaine, ketamine).

Monitoring of anaesthesia

Physical monitoring of the cardiovascular system includes evaluation of pulse rate and strength, capillary refill time, and auscultation of the heart. Heart rate usually does not change as anaesthesia deepens in horses and normally ranges between 25 and 50 beats per minute during anaesthesia. Rates less than 25 may require the administration of anticholinergics to increase heart rate. Heart rates in excess of 50 may indicate light planes of anaesthesia hypotension, hypercarbia or hypoxaemia. Pulse strength will decrease as the depth of anaesthesia increases. The pulse pressure is a reflection of the difference between systolic and diastolic blood pressure and can be attained by gauging the digital pressure required to occlude the pulse in a peripheral artery. Capillary refill time may be measured by blanching the gums and counting the seconds until the colour returns. Colour of the mucous membranes combined with capillary refill is used as an index of perfusion. Alterations from the normal pink colour of the gums may indicate poor perfusion, toxaemia, cyanosis, or hypercarbia.  […]